Alcohol and other drug (AOD) abuse among adolescents is a major public health problem resulting in significant negative outcomes and extraordinary long-term costs. The rates of AOD abuse among youth in the justice system are twice the rates among youth without justice involvement. Further, youth offenders who abuse AOD engage in more severe delinquency and continue offending as adults, and their rate of engagement in HIV/STI sexual risk behaviors is alarming. Therefore, widespread access and delivery of effective AOD interventions to juvenile offenders is of considerable importance. Unfortunately, significant challenges exist for meeting the treatment needs of justice-involved youth. Although juvenile offenders are routinely referred to community-based providers for treatment, less than 1 in 5 are able to obtain such treatment. Further, for youth and families who are able to overcome barriers and engage with service providers, it is unlikely that they will receive an intervention that is evidence-based. In light of this context, innovative strategies clearly are needed to improve juvenile offenders' access to evidence-based practices for AOD abuse. Thus, the overriding purpose of the proposed study is to increase the access to such an evidence- based practice (Contingency Management [CM]) among youth in the juvenile justice system. This study leverages and extends the investigative team's work in CM efficacy, delivery, and technology transfer in juvenile justice settings, as well as 30+ years of collaboration with juvenile justice. We posit that juvenile probation officers (JPOs) are in an ideal position to delier an AOD evidence-based practice to youth because of their intensive involvement and frequent contact with the youth offenders under their supervision. Further, CM is ideal for JPOs to learn and implement because it is highly specified and low in complexity relative to other AOD evidence-based practices for youth. Also, JPOs regularly monitor their probationers' substance use via frequent biological screens and implement consequences based on results, making CM consistent with JPOs' work. The proposed research randomizes 36 JPOs to 2 conditions: CM versus control (usual JPO services), and then randomizes 504 AOD abusing adolescent probationers across those 2 conditions. This research would provide (1) evidence for the feasibility of JPOs to deliver an AOD abuse intervention, (2) initial evidence of clinical efficacy for JPOs as service delivery providers [to address clinical public health outcomes of AOD use, criminal activity, and HIV/STI sexual risk behaviors], and (3) identify any barriers that would need to be addressed for JPOs to deliver such services. The primary motivation for this application is the clear public health need for improving and expanding delivery of AOD abuse interventions in the juvenile justice system. The ultimate outcome would be decreased AOD use and other public health-related behaviors (i.e., criminal behaviors, HIV/STI sexual risk behaviors) among these high-risk adolescents.